925 resultados para Crack Tip Opening Displacement (Ctod)
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A multicomponent indicator displacement assay ( MIDA) based on an organometallic receptor and three dyes can be used for the identification and quantification of nucleotides in aqueous solution at neutral pH.
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Concrete paving is often at a disadvantage in terms of pavement type selection due to the time of curing required prior to opening the pavement to traffic. The State of Iowa has been able to reduce traffic delay constraints through material selection and construction methods to date. Methods for monitoring concrete strength gain and quality have not changed since the first concrete pavements were constructed in Iowa. In 1995, Lee County and the Iowa DOT cooperated in a research project, HR-380, to construct a 7.1 mile (11. 43 km) project to evaluate the use of maturity and pulse velocity nondestructive testing (NDT) methods in the estimation of concrete strength gain. The research identified the pros and cons of each method and suggested an instructional memorandum to utilize maturity measurements to meet traffic delay demands. Maturity was used to reduce the traffic delay opening time from 5-7 days to less than 2 days through the implementation of maturity measurements and special traffic control measures. Recommendations on the development of the maturity curve for each project and the location and monitoring of the maturity thermocouples are included. Examples of equipment that could easily be used by project personnel to estimate the concrete strength using the maturity methods is described.
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The Brianconnais area is explained as a large scale exotic terrain separating from Europe during the opening of the Valais ocean. It's displacement history during the Alpine evolution allows to replace older concepts of multiple oceans separating narrow strips of continental crust.
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A mechanical gauge was developed to monitor the movement of crack or joint openings in portland cement concrete structures, in general, and portland cement concrete pavements in particular. Designed to be inexpensive and simple to operate, this gauge is capable of recording maximum, minimum, and instantaneous crack or joint openings. Specific recommendations were made for recording minimum and maximum pavement temperature over the monitoring period. The report was written as a set of guidelines for design, fabrication, installation, and operation of the gauge as well as the temperature measuring device.
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The Iowa DOT has been using the AASHTO Present Serviceability Index (PSI) rating procedure since 1968 to rate the condition of pavement sections. A ride factor and a cracking and patching factor make up the PSI value. Crack and patch surveys have been done by sending crews out to measure and record the distress. Advances in video equipment and computers make it practical to videotape roads and do the crack and patch measurements in the office. The objective of the study was to determine the feasibility of converting the crack and patch survey operation to a video recording system with manual post processing. The summary and conclusions are as follows: Video crack and patch surveying is a feasible alternative to the current crack and patch procedure. The cost per mile should be about 25 percent less than the current procedure. More importantly, the risk of accidents is reduced by getting the people and vehicles off the roadway and shoulder. Another benefit is the elimination of the negative public perceptions of the survey crew on the shoulder.
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This Phase II follow-up study of IHRB Project TR-473 focused on the performance evaluation of rubblized pavements in Iowa. The primary objective of this study was to evaluate the structural condition of existing rubblized concrete pavements across Iowa through Falling Weight Deflectometer (FWD) tests, Dynamic Cone Penetrometer (DCP) tests, visual pavement distress surveys, etc. Through backcalculation of FWD deflection data using the Iowa State University's advanced layer moduli backcalculation program, the rubblized layer moduli were determined for various projects and compared with each other for correlating with the long-term pavement performance. The AASHTO structural layer coefficient for rubblized layer was also calculated using the rubblized layer moduli. To validate the mechanistic-empirical (M-E) hot mix asphalt (HMA) overlay thickness design procedure developed during the Phase I study, the actual HMA overlay thicknesses from the rubblization projects were compared with the predicted thicknesses obtained from the design software. The results of this study show that rubblization is a valid option to use in Iowa in the rehabilitation of portland cement concrete pavements provided the foundation is strong enough to support construction operations during the rubblization process. The M-E structural design methodology developed during Phase I can estimate the HMA overlay thickness reasonably well to achieve long-lasting performance of HMA pavements. The rehabilitation strategy is recommended for continued use in Iowa under those conditions conducive for rubblization.
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Early entry sawing applies sawing earlier and more shallowly than conventional sawing and is believed to increase sawing productivity and reduce the cost of the joint sawing operations. However, some early entry sawing joints (transverse joints) in Iowa were found to experience delayed cracking, sometimes up to 30 days. A concern is whether early entry sawing can lead to late-age random cracking. The present study investigated the effects of different sawing methods on random cracking in portland cement concrete (PCC) pavements. The approach was to assess the cracking potential at sawing joints by measuring the strain development of the concrete at the joints using concrete embedment strain gages. Ten joints were made with the early entry sawing method to a depth of 1.5 in., and two strain gages were installed in each of the joints. Another ten joints were made with the conventional sawing method, five of which were sawed to a depth of one-third of the pavement thickness (3.3 in.), and the other five of which were sawed to a depth of one-quarter of the pavement thickness (2.5 in.). One strain gage was installed in each joint made using conventional sawing. In total, 30 strain gages were installed in 20 joints. The results from the present study indicate that all 30 joints cracked within 25 days after paving, though most joints made using early entry sawing cracked later than the joints made using conventional sawing. No random cracking was observed in the early entry sawing test sections two months after construction. Additionally, it was found that the strain gages used were capable of monitoring the deformations at the joints. The joint crack times (or crack initiation time) measured by the strain gages were generally consistent with the visual observations.
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The seven subunit Arp2/3 complex is a highly conserved nucleation factor of actin microfilaments. We have isolated the genomic sequence encoding a putative Arp3a protein of the moss Physcomitrella patens. The disruption of this ARP3A gene by allele replacement has generated loss-of-function mutants displaying a complex developmental phenotype. The loss-of function of ARP3A gene results in shortened, almost cubic chloronemal cells displaying affected tip growth and lacking differentiation to caulonemal cells. In moss arp3a mutants, buds differentiate directly from chloronemata to form stunted leafy shoots having differentiated leaves similar to wild type. Yet, rhizoids never differentiate from stem epidermal cells. To characterize the F-actin organization in the arp3a-mutated cells, we disrupted ARP3A gene in the previously described HGT1 strain expressing conditionally the GFP-talin marker. In vivo observation of the F-actin cytoskeleton during P. patens development demonstrated that loss-of-function of Arp3a is associated with the disappearance of specific F-actin cortical structures associated with the establishment of localized cellular growth domains. Finally, we show that constitutive expression of the P. patens Arp3a and its Arabidopsis thaliana orthologs efficiently complement the mutated phenotype indicating a high degree of evolutionary conservation of the Arp3 function in land plants.
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The objective of this work was to evaluate hematological, biochemical and ruminant parameters for diagnosis and treatment of the left displaced abomasum (LDA) in dairy cows, in the Plateau Region of Rio Grande do Sul, Brazil. Ruminant fluid, blood and urine samples were collected from 20 cows suffering LDA and from 20 healthy cows (control). The cows with LDA showed lower values of daily milk production, body weight and corporal condition score. The use of pH reagent strips showed to be functional in the field, when compared to a digital pH meter. Ruminant dynamics was damaged in cows affected by LDA, as it was evidenced by the higher reduction time of methylene blue. Serum values of lactate, beta-hydroxybutyrate, urea, albumin, free fatty acids and cholesterol shows to be auxiliary tools in the LDA characterization.
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Reflective cracks form in pavements when hot-mix asphalt (HMA) overlays are placed over jointed and/or severely cracked rigid and flexible pavements. In the first part of the research, survival analysis was conducted to identify the most appropriate rehabilitation method for composite pavements and to evaluate the influence of different factors on reflective crack development. Four rehabilitation methods, including mill and fill, overlay, heater scarification (SCR), and rubblization, were analyzed using three performance indicators: reflective cracking, international roughness index (IRI), and pavement condition index (PCI). It was found that rubblization can significantly retard reflective cracking development compared to the other three methods. No significant difference for PCI was seen among the four rehabilitation methods. Heater scarification showed the lowest survival probability for both reflective cracking and IRI, while an overlay resulted in the poorest overall pavement condition based on PCI. In addition, traffic level was found not to be a significant factor for reflective cracking development. An increase in overlay thickness can significantly delay the propagation of reflective cracking for all four treatments. Soil types in rubblization pavement sites were assessed, and no close relationship was found between rubblized pavement performance and subgrade soil condition. In the second part of the research, the study objective was to evaluate the modulus and performance of four reflective cracking treatments: full rubblization, modified rubblization, crack and seat, and rock interlayer. A total of 16 pavement sites were tested by the surface wave method (SWM), and in the first four sites both falling weight deflectometer (FWD) and SWM were conducted for a preliminary analysis. The SWM gave close concrete layer moduli compared to the FWD moduli on a conventional composite pavement. However, the SWM provided higher moduli for the rubblized concrete layer. After the preliminary analysis, another 12 pavement sites were tested by the SWM. The results showed that the crack and seat method provided the highest moduli, followed by the modified rubblization method. The full rubblization and the rock interlayer methods gave similar, but lower, moduli. Pavement performance surveys were also conducted during the field study. In general, none of the pavement sites had rutting problems. The conventional composite pavement site had the largest amount of reflective cracking. A moderate amount of reflective cracking was observed for the two pavement sites with full rubblization. Pavements with the rock interlayer and modified rubblization treatments had much less reflective cracking. It is recommended that use of the modified rubblization and rock interlayer treatments for reflective cracking mitigation are best.
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New reconstructions of the Western Alps from late Early Jurassic till early Tertiary are proposed. These reconstructions use deep lithospheric data gathered through recent seismic surveys and tomographic studies carried out in the Alps. The present day position, under the Po plain, of the southern limit of the European plate (fig. 1), allows to define the former geometry of the Brianconnais peninsula. The Brianconnais domain is regarded as an exotic terrane formerly belonging to the European margin until Late Jurassic, then transported eastward during the drift of Iberia (fig. 5). Therefore, on a present day Western Alps cross section, a duplication of the European continental margin can be recognized (fig. 10). Stratigraphic and sedimentological data along a zone linking the Pyrenean fracture zone to the Brianconnais, can be related to a rifting event starting in Oxfordian time. This event is responsible for the Late Jurassic till mid-Cretaceous drift of Iberia opening, first the northern Atlantic, then the Gulf of Biscay. Simultaneously, the drift of the Brianconnais will open the Valais ocean and close the Piemontese ocean. The resulting oblique collision zone between the Brianconnais and the Apulian margin generates HP/LT metamorphism starting in Early Cretaceous. The eastward drift of the Brianconnais peninsula will eventually bring it in front of a more northerly segment of the former European margin. The thrusting of the Brianconnais unto that margin takes place in early Tertiary (fig. 9), following the subduction of the Valais ocean. The present nappe pile results not only from continent/continent frontal collision, but also from important lateral displacement of terranes, the most important one being the Brianconnais. The dilemma of `'en echelon'' oceanic domains in the Alps is an outcome of these translations. A solution is found when considering the opening of a Cretaceous Valais ocean across the European margin, running out eastward into the Piemontese ocean, where the drift is taken up along a former transform fault and compensated by subduction under the Apulian margin (fig. 8). In the Western Alps we are then dealing with two oceans, the Piemontese and the Valaisan and a duplicated European margin. In the Eastern Alps the single Piemontese ocean is cut by newly created oceanic crust. All these elements will be incorporated into the Penninic structural domain which does not represent a former unique paleogeographic area, it is a composite accretionary domain squeezed between Europe and Apulia.
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OBJECTIVES: To test the validity of a simple, rapid, field-adapted, portable hand-held impedancemeter (HHI) for the estimation of lean body mass (LBM) and percentage body fat (%BF) in African women, and to develop specific predictive equations. DESIGN: Cross-sectional observational study. SETTINGS: Dakar, the capital city of Senegal, West Africa. SUBJECTS: A total sample of 146 women volunteered. Their mean age was of 31.0 y (s.d. 9.1), weight 60.9 kg (s.d. 13.1) and BMI 22.6 kg/m(2) (s.d. 4.5). METHODS: Body composition values estimated by HHI were compared to those measured by whole body densitometry performed by air displacement plethysmography (ADP). The specific density of LBM in black subjects was taken into account for the calculation of %BF from body density. RESULTS: : Estimations from HHI showed a large bias (mean difference) of 5.6 kg LBM (P<10(-4)) and -8.8 %BF (P<10(-4)) and errors (s.d. of the bias) of 2.6 kg LBM and 3.7 %BF. In order to correct for the bias, specific predictive equations were developed. With the HHI result as a single predictor, error values were of 1.9 kg LBM and 3.7 %BF in the prediction group (n=100), and of 2.2 kg LBM and 3.6 %BF in the cross-validation group (n=46). Addition of anthropometrical predictors was not necessary. CONCLUSIONS: The HHI analyser significantly overestimated LBM and underestimated %BF in African women. After correction for the bias, the body compartments could easily be estimated in African women by using the HHI result in an appropriate prediction equation with a good precision. It remains to be seen whether a combination of arm and leg impedancemetry in order to take into account lower limbs would further improve the prediction of body composition in Africans.
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A major problem with holographic optical tweezers (HOTs) is their incompatibility with laser-based position detection methods, such as back-focal-plane interferometry (BFPI). The alternatives generally used with HOTs, like high-speed video tracking, do not offer the same spatial and temporal bandwidths. This has limited the use of this technique in precise quantitative experiments. In this paper, we present an optical trap design that combines digital holography and back-focal-plane displacement detection. We show that, with a particularly simple setup, it is possible to generate a set of multiple holographic traps and an additional static non-holographic trap with orthogonal polarizations and that they can be, therefore, easily separated for measuring positions and forces with the high positional and temporal resolutions of laser-based detection. We prove that measurements from both polarizations contain less than 1% crosstalk and that traps in our setup are harmonic within the typical range. We further tested the instrument in a DNA stretching experiment and we discuss an interesting property of this configuration: the small drift of the differential signal between traps.
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Chaotic systems, when used to drive copies of themselves (or parts of themselves) may induce interesting behaviors in the driven system. In case the later exhibits invariance under amplification or translation, they may show amplification (reduction), or displacement of the attractor. It is shown how the behavior to be obtained is implied by the symmetries involved. Two explicit examples are studied to show how these phenomena manifest themselves under perfect and imperfect coupling.
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The Universitat Oberta de Catalunya (Open University of Catalonia, UOC) is an online university that makes extensive use of information and communication technologies to provide education. Ever since its establishment in 1995, the UOC has developed and tested methodologies and technological support services to meet the educational challenges posed by its student community and its teaching and management staff. The know-how it has acquired in doing so is the basis on which it has created the Open Apps platform, which is designed to provide access to open source technical applications, information on successful learning and teaching experiences, resources and other solutions, all in a single environment. Open Apps is an open, online catalogue, the content of which is available to all students for learning purposes, all IT professionals for downloading and all teachers for reusing.To contribute to the transfer of knowledge, experience and technology, each of the platform¿s apps comes with full documentation, plus information on cases in which it has been used and related tools. It is hoped that such transfer will lead to the growth of an external partner network, and that this, in turn, will result in improvements to the applications and teaching/learning practices, and in greater scope for collaboration.Open Apps is a strategic project that has arisen from the UOC's commitment to the open access movement and to giving knowledge and technology back to society, as well as its firm belief that sustainability depends on communities of interest.